1. Field of the Invention
The present invention generally relates to a display apparatus and, more particularly, to a spectacle type retina direct display apparatus in which a video image is directly projected onto the retinas of both eyes and displayed thereon.
2. Description of the Prior Art
Most video information is generally displayed on a monitor TV (television) receiver or on a screen, and a real image thereof is projected onto the viewer's retinas through the eyeballs, thereby being perceived by the viewer.
According to the above-described video apparatus, however, the monitor screen surface is projected onto one portion of the retina so that the displayed image is not so powerful for the viewer. For this reason, a monitor TV receiver and a screen projection apparatus of a large picture screen are widely utilized. It is, however, unavoidable that these systems need a large-scale video apparatus and a wide video space.
As one of the methods for obtaining a powerful large picture in a relatively small video space, a TV display apparatus of a spectacle type is proposed as disclosed, for example, in Japanese Laid-Open Utility Model Gazette No. 48-16726.
This display system is a magnifying glass system in which an image is magnified by an optical system and a virtual image is viewed by the viewer. In this system as shown in FIG. 1, a light output from an image A-B is enlarged by a lens 1 and projected onto a retina 3 through a crystalline lens 2, but the image perceived at that time is a virtual image as shown by A'-B' in FIG. 1.
As a consequence, if the magnifying ratio of the lens 1 is increased, an aberration causes a blur to occur in which the peripheral portion of the image becomes out of focus, thus considerably depriving the picture of the power.
Further, the eyesight adjustment for matching the apparatus with viewers becomes indispensable. If the display apparatus of this type is utilized for a long period of time after the adjustment of eyesight, the eye's muscles are extremely fatigued because the focal point of the crystalline lens 2 must be adjusted.
A real image system of the prior art to which the present invention is applied will be explained next with reference to FIG. 2.
As shown in FIG. 2, an optical system of this real image system is fundamentally comprised of a point-source of light 11, an image plate 12 illuminated by this point-source of light 11 and an eye lens 13 of a short focal length located to become substantially one body with the image plate 12. According to this arrangement, an image is projected by the above-mentioned optical system onto a retina 15 as a real image as shown in FIG. 2.
Particularly, in the case of both eyes, the adjustment of a distance between pupils is further required so that, even when the above apparatus is formed as a spectacle type, the apparatus becomes large in size and complicated in arrangement.